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ECE :: Electromagnetic Field Thoery

  1. In figure the voltage distribution on a vertical earthed antenna is represented by

  2. A.
    curve A
    B.
    curve B
    C.
    curve C
    D.
    curve D

  3. The direction in a Yagi Uda antenna

  4. A.
    is longer than the radiating element
    B.
    is shorter than the radiating element
    C.
    can be longer or shorter than the radiating element
    D.
    does not exist

  5. In cell phone antennas are

  6. A.
    monopole
    B.
    loops
    C.
    helical
    D.
    lens

  7. Antenna commonly used for microwave links are

  8. A.
    loop antennas
    B.
    log periodic antennas
    C.
    paraboloidal dishes
    D.
    rhombic antennas

  9. For a good conducting medium the intrinsic impedance is

  10. A.
    σωμp/2
    B.
    ωμ /σ ∠45°
    C.
    ωμ/σp/2
    D.
    ωμ/σ ∠0°

  11. The force in a magnetic field is given by F = qvB

  12. A.
    F and q are perpendicular and v and B are perpendicular
    B.
    F and q only are perpendicular to each other
    C.
    F and v, F and B are mutually perpendicular to each other and v and B at any angle between them
    D.
    All the four components are perpendicular to each other

  13. An electromagnetic wave is incident normally on a dielectric boundary. It is

  14. A.
    totally reflected
    B.
    partially reflected and partially refracted
    C.
    totally absorbed
    D.
    none of the above

  15. According to maximum power transfer theorem, if the load is inductive, the source should be

  16. A.
    inductive
    B.
    capacitive
    C.
    resistive
    D.
    any of the above

  17. According to Siegel and Labus, antenna can be treated as

  18. A.
    closed transmission line
    B.
    shorted transmission line
    C.
    earthed transmission line
    D.
    opened-out transmission line

  19. Given figure shows a 90° sector of spherical reflector with vertex 'V', centre of curvature 'C' and equal distances VD, DF, FE and EC. When a beam of EM wave is incident parallel to the axis, all the energy will pass through the region

  20. A.
    VD
    B.
    DF
    C.
    EF
    D.
    EC